The antigenic reactive sites of native hen egg-white lysozyme will be delineated. Lysozyme will be cleaved enzymatically and chemically to yield fragments with intact disulfide bonds. The immunochemistry of the peptide fragments will be studied by a variety of inhibition and binding techniques. After narrowing down the third antigenic site by chemical methods to a conveniently small sixe, it will be finally delineated by synthesis of appropriate peptides corresponding to various parts of the chemically-delineated region. Disulfide-peptides and "surface-simulation" peptides will be synthesized and studied. All the antigenic sites of lysozyme will be prepared by organic synthesis. Antibodies to the sites will be prepared from antisera to lysozyme and by direct immunization with site-carrier conjugates. The latter will be prepared with various site combinations. The specificity, binding affinity, restricted heterogeneity of the antibodies will be studied as well as their ability to inhibit the enzymic activity of lysozyme. The maturation and maintenance of the immune response to the antigenic sites and their relative immunodominance will be studies in rabbits and goats from two days up to a year. Factors influencing the immune response during the immunization schedule will be studied.